Contributed Talk - Friday, 17 September I 10:10 AM (CEST)

Mathaeus Tschaikowsky: "Changes in the supramolecular collagen structure in human early osteoarthritic cartilage"

Mathaeus Tschaikowsky ¹ ², Sofia Brander ¹, Bernd Rolauffs ², Bizan N. Balzer¹ ³ and Thorsten Hugel ¹ ³

¹ Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany

² G.E.R.N. Center for Tissue Replacement, Regeneration & Neogenesis, Department of Orthopedics and Trauma Surgery, Medical Center - University of Freiburg; Faculty of Medicine, University of Freiburg, Freiburg, Germany

³ Cluster of Excellence livMatS @ FIT – Freiburg Center for Interactive Materials and Bioinspired Technologies, Freiburg, Germany

Osteoarthritis (OA) is a joint disease affecting millions of patients worldwide. During OA, articular cartilage tissue is destroyed. A main structural component of cartilage is the network of collagen type II-rich fibers. Here, a sensitive biomarker for early OA is used, namely the spatial organization of superficial chondrocytes, to discriminate between early OA stages¹. Changes in the collagen network of the articular surfaces from knee joints of patients are detected via high-resolution AFM imaging under native conditions². The results show that firstly, the overall thickness of collagen fibers decreases during OA. Secondly, the number of thick fiber bundles (>100 nm) decreases at a very early stage of the disease with an absence of such fibers in samples characterized by a late OA chondrocyte organization. In addition, our latest biochemical analysis reveals the presence of collagen type I in cartilage showing a late OA chondrocyte organization. This data demonstrates for the first time the formation of collagen type I-rich fibrocartilage in macroscopically intact cartilage, distant from OA lesions. Taken together, the data point at a mechanism for the loss of tissue functionality in early OA cartilage in which the thickness of collagen fibers decreases, followed by the formation of mechanically inferior fibrocartilage.

References:

[1] Tschaikowsky et al., Osteoarthritis and Cartilage 29 (2) (2021), p. 269–279.

[2] Tschaikowsky et al., Acta Biomaterialia 126 (2021), p. 315–325.

Figure. AFM image recorded under native conditions: Articular surface of a human femoral condyle2.